Update changelog for 6.2.0 release.

CHANGELOG.md

+# 6.2.0
+
+## Features
+
+### New processes
+
+- HeatTransportBHE process supporting 1U, CXA, and CXC BHE types. #2221, #2332,
+  #2271, #2275
+- Staggered implementation of a thermo-mechanical with phasefield process. #2102
+- Richards mechanics process. #2189
+- Small deformation process with non-local integration of damage. #2294
+- Staggered implementation of phasefield process. #2052
+- ComponentTransport process in revised formulation. #2200
+- Multi-component transport process. #2304
+
+### Other process' changes
+
+- A Jacobian tester: a process's Jacobian assembly can be compared to a
+  numerical Jacobian (mostly for development. #2238
+- Add `setInitialConditions()` call to processes and local assemblers. #2334
+- Several bug fixes for LIE/HM process including "fracture into matrix
+  leak-off", Darcy velocity output in the fracture. #2129
+- Support for intersecting fractures (x-crossing and t-junction) in LIE/SD
+  process. #2235, #2293
+- Fixed the calculation of the Darcy velocity in staggered TH. #2127
+
+#### Numerics
+
+- Staggered scheme for coupled processes with different orders of elements.
+  #2016
+- Subdomain deactivation within time intervals. #2297
+- Add a driver for an iteration based time stepping algorithm. #2318
+
+#### Boundary condition
+
+- Implementation of Python boundary conditions. #2170
+- Implementation of constraint boundary conditions. #2145
+- Dirichlet boundary condition within a time interval. #2272
+- BoundaryElementSearch: Return bulk element id and bulk element face id. #2125
+- Removed Neumann boundary condition for displacement jumps in LIE processes.
+  #2153
+
+#### Source term
+
+- Use parameter for source terms. #2061
+- Volumetric source terms implementation. #2220, #2234, #2241, #2261
+
+#### Input and output
+
+- Writing and reading of integration point data. Implemented sigma and epsilon
+  output for some processes. #2071, #2203, #2324
+- Add input of vtu-meshes for boundary conditions additionally to the gml input.
+  This is later used by the heterogeneous parameters and source terms. #2140,
+  #2141, #2156
+- Parameters may now be explicitly defined on arbitrary subdomains. This merges
+  the Heterogeneous Dirichlet and Neumann boundary conditions with their,
+  previously only homogeneous, counterparts. #2376
+- Parameters now support space-dependent function input via exprtk library.
+  #2325, #2339
+- Output of primary variables on arbitrary subdomains. #2372, #2299
+- Output is possible at specific times for adaptive time stepping and
+  evolutionaryPIDController. #2079
+- Calculate and output specific flux. #2411
+- Enable surface flux calculation for component transport process. #2168
+- Interpolated pressure (on higher order elements' nodes) output for
+  Richards-mechanics and hydro-mechanics processes. #2228
+- Improve output of nodal aperture and aperture vector in LIE/HM. #2050
+- Add output of nodal forces and hydraulic flow in mechanics and coupled
+  mechanics processes, SD, HM, LIE/SD, LIE/HM. #2118
+- Enable surface flux calculation for HT process. #2132
+- Fixed pvd output. #2036
+
+### Material model changes
+
+- BGRa creep model. #2167
+- New cohesive zone mode I fracture model for LIE processes. #2142, #2157
+- Add MFront/TFEL solid constitutive relation support via.
+  MFrontGenericInterfaceSupport library. CMake option `OGS_USE_MFRONT`. #2259
+- Infrastructure for multi-phase, multi-component material properties library.
+  #2303
+- Anisotropic tensors may now be given in given local coordinate system. #2370
+- Non-constant density model implementation in HC process. #2200
+- Add second derivatives of permeability functions in Richards flow. #2188
+- Different solid material models can now be defined on different materialIDs.
+  #2216, #2262, #2270
+- Move solid constitutive relation creation in single place. #2160
+
+### Testing and documentation
+
+- Migrated Appveyor tests to [Azure
+  Pipelines](https://dev.azure.com/ogsci/ogs/_build). #2342
+- Added cppcheck, clang-tidy and include-what-you-use. #2078, #2328, #2377
+- Added check for header standalone compilation, can be enabled with
+  'OGS_CHECK_HEADER_COMPILATION=ON'. #2043
+- Jenkins shows nice summaries of compiler warnings. #2206
+- Large tests are fixed and run on Jenkins upon master merge. #2056, #2155
+- Re-enabled code coverage reports (for the testrunner only) with
+  [Codecov](http://codecov.io/gh/ufz/ogs). #2333, #2336
+- Commits containing `[ci skip]` in the commit message do not trigger a Jenkins
+  build.
+- Add `vtkdiff` test configuration to project files, s.t. the vtkdiff tests are
+  performed after successful run comparing output to reference files. This
+  possibility is also reflected in a new CMake function `OgsTest` as an
+  alternative to the `AddTest`. #2255, #2257
+
+### New tools
+
+- `TecPlotTools`: splitting files containing multiple zones into seperate
+  TecPlot files. #2114
+- `TecPlot-Reader`: converting TecPlot rasters into OGS meshes (one file per
+  zone, containing all variables as scalar arrays). #2114
+- [`constructMeshesFromGeometry`](https://www.opengeosys.org/docs/tools/model-preparation/constructmeshesfromgeometry/):
+  Construction of boundary meshes from bulk mesh and gml files. #2144
+- [`identifySubdomains`](https://www.opengeosys.org/docs/tools/model-preparation/identifysubdomains/):
+  Identification of boundary meshes (or any subdomains in general) in the bulk
+  mesh. Performs geometrical tests and creates and verifies necessary
+  `bulk_node_ids` and `bulk_element_ids` maps. #2227, #2252
+- `Mesh2Raster`: converts 2D OGS meshes into raster files of arbitrary pixel
+  size, where node elevation is represented by pixel value. #2367
+- `GocadSGridReader` tool reading the Gocad/SKUA stratigraphic grid format and
+  writing the data in the vtu format. #2316
+
+### New tools and CLI usage
+
+- `ogs --help` shows the given CMake options. #2210
+- Unify command line version info output. #2194
+- Rewrite `partmesh` tool and add partitioning of boundary meshes (or subdomains
+  in general) according to the partition of the bulk mesh. #2159, #2178, #2195
+- Add new features to `ExtractSurface` tool. #2387, #2401
+- updated utility `moveMeshNodes`: algorithm for mesh on mesh mapping now
+  calculates exact node elevation instead of using interpolation. #2390
+
+### Data Explorer
+
+- Listing of source terms and boundary conditions in Data Explorer DataView (no
+  visualisation yet). #2110
+- Mesh element removal can now remove elements based on value ranges of
+  arbitrary scalar arrays (currently only int- and double arrays are supported).
+  #2115
+- added custom VTK filter to represent raster data as point clouds. #2121
+- geometrical points can now be converted into station points. #2369
+- fixed issue with geometrical surfaces not being loaded correctly. #2388
+
+### Other notable code changes
+
+- C++17 standard is enabled and is allowed in the production code (given the
+  compiler support). #2298
+- Separate monolithic ProcessLib into individual processes. Now it is possible
+  to build ogs with selected processes only. This also improves linking times.
+  #2017
+- Parameters are extracted in own library. #2413
+- Port secondary variable extrapolation and output for PETSc builds. #2082
+- Extend Kelvin mapping functions and move implementation to MathLib. #2060,
+  #2075, #2044
+- Collect generic algorithms in single header file. #2161
+- Remove unused MeshSubsets class. #2135
+- Removed writing of xsd header in XML files, #2198
+
+## Infrastructure
+
+- Migrated LFS storage from GitLab to [Artifactory](https://ogs.jfrog.io/ogs).
+  #2359
+- Optimized ctest runtime by starting long-running benchmarks first. #2310
+- Proper RPATH handling for shared library installations. #2208
+- [Package OGS inside
+  container](https://www.opengeosys.org/docs/userguide/basics/container/) with
+  [Singularity](https://www.sylabs.io/singularity/); [more
+  docs](https://www.opengeosys.org/docs/devguide/advanced/singularity/). #2193,
+  #2356
+- Migrated opengeosys.org to a static site generator ([Hugo](https://gohugo.io))
+  unifying documentation and general OGS info. #2088, #2095, #2123
+- Speed-up CMake run time. #2072, #2392
+
+### CMake options changes
+
+- `OGS_USE_PYTHON` enables Python BCs. #2170
+- `OGS_BUILD_TESTS` was renamed to `BUILD_TESTING`. #2350
+- Added `OGS_USE_CVODE`. #2344
+- Added `OGS_BUILD_PROCESSES` for `;`-separated list of processes to build.
+  #2233
+- `OGS_USE_CONAN=ON` is now the default when `conan` was found. #2207
+
+### Version info
+
+- CMake minimum version 3.10
+- Visual Studio minimum (and tested) version 2017
+- GCC minimum version 6.2 (tested: 6.4)
+- Clang minimum version 3.5 (tested: 7.0)
+- Boost minimum version 1.66.0
+- VTK minimum version 8.1. #2158
+- Qt tested version 5.11.2
+- Python tested version 3.7.2
+
+
 # 6.1.0
 
 The changes since the prerelease 6.1.0-rc1 contain few bug fixes and